I'm finally creeping up on a set up that has eliminated the off-idle stumble on my 302. I've got the E'brk 1406 (600 cfm elec choke) carb on a rebuilt 302 with AFR 165 heads and a mild cam.

The car would ALWAYS hesitate off idle no matter which rod/jet combo's i used from the calibration kit for my carb. After doing a little more research, i discovered that the manual choke 600 cfm carb (1405) was jetted differently from the factory than the electric choke model. Today, i put in jets & metering rods that very nearly duplicated the 1405 set up and the hesitation is greatly reduced.

My questions is this... for the folks out there who are using an Edelbrock 600 carb on a "warmed up" 302, what rod/jet/step up springs are you using?

I just want to know if I'm actually moving towards a solution, or just covering up a problem somewhere else in the engine.

THanks...

 

A hesitation is going to be either a lean condition or a really rich condition. It's more commonly a lean condition, because it has to be really rich to cause a hesitation issue. I'd suspect improper idle mixture, lean cruise mode jetting, or improper stepup springs.

I've found that Edelbrock likes to put really strong stepup springs in at the factory, which keeps the carb in cruise mode for too long. Swap those out for some 3" or 4" springs and see what happens.

Also, how's your timing?

 

i recently fixed the off-idle stumble i had by readjusting my idle mixture screws. it was idling at a nice rpm, but that was only because i was using a lot of mixture and barely any idle speed screw.

so i leaned out the mixture and bumped up the idle speed screw and viola...hesitation gone.

so in my case, it was getting too much fuel.